Systems and methods for metrology recipe and model generation

ABSTRACT

Systems and methodologies are disclosed for generating setup information for use measuring process parameters associated with semiconductor devices. A system comprises an off-line measurement instrument to measure an unpatterned wafer and a setup information generator to generate setup information according to the unpatterned wafer measurement. The system then provides the setup information to a process measurement system for use in measuring production wafers in a semiconductor manufacturing process.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/132,553, filed Apr. 24, 2002 now U.S. Pat. No. 7,089,075. Thisapplication also claims the benefit of U.S. Provisional Application Ser.No. 60/288,748, entitled “Systems And Method For Metrology Recipe AndModel Generation” and filed on May 4, 2001, the entirety of which isincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to the art of semiconductor devicemanufacturing and fabrication, and more particularly to optimizedsystems and methodologies for creating setup information forsemiconductor device measurement systems.

BACKGROUND OF THE INVENTION

In the semiconductor industry there is a continuing trend toward higherdevice densities. To achieve these high densities there have been, andcontinue to be, efforts toward scaling down the device dimensions onsemiconductor wafers. In order to accomplish such a high device packingdensity, smaller feature sizes are required. These may include the widthand spacing of interconnecting lines and the surface geometry such asthe corners and edges of various features. The requirement of smallfeatures with close spacing between adjacent features requireshigh-resolution photo-lithographic processes as well as high resolutionmetrology and inspection instruments and systems.

Lithography refers generally to processes for pattern transfer betweenvarious media. It is a technique used for integrated circuit fabricationin which, for example, a silicon wafer is coated uniformly with aradiation-sensitive film (e.g., a photoresist), and an exposing source(such as ultraviolet light, x-rays, or an electron beam) illuminatesselected areas of the film surface through an intervening mastertemplate (e.g., a mask or reticle) to generate a particular pattern. Theexposed pattern on the photoresist film is then developed with a solventcalled a developer which dissolves either the exposed pattern or thecomplimentary unexposed pattern, depending on the type of photoresist(i.e., positive or negative resist). After developing, the wafer has aphotoresist mask corresponding to the desired pattern on the siliconwafer for further processing.

In addition to lithographic processes, other process steps in thefabrication of semiconductor wafers require higher resolution processingand measurement equipment in order to accommodate ever shrinking featuresizes and spacing. Measurement instruments and systems are used toinspect semiconductor devices in association with manufacturingproduction line quality control applications as well as with productresearch and development. The ability to measure and/or view particularfeatures in a semiconductor workpiece allows for adjustment ofmanufacturing processes and design modifications in order to producebetter products, reduce defects, etc. For instance, device measurementsof film thicknesses, critical dimensions (CDs), profiles, and overlayregistration may be used to make adjustments in one or more such processsteps in order to achieve the desired product quality. Accordingly,various metrology and inspection tools and instruments have beendeveloped to map and record semiconductor device features, such asscanning electron microscopes (SEMs), atomic force microscopes (AFMs),scatterometers, spectroscopic ellipsometers (SEs), and the like.

One particular type of measurement system is a scatterometer, which isdifferent from conventional film measurements.. Scatterometry is atechnique for extracting information about a structure or stackedstructures upon which an incident light has been directed. Inparticular, scatterometry involves extracting information from gratingsover other gratings or from gratings over a film stack. As indicated byits name, scatterometry is primarily concerned with the shapes of twoand three dimensional structures in order to ascertain and determine theroughness of the layers or the non-planarity or non-parallelism of theplanes. The structures of interest scatter light in ways that flat,one-dimensional layers do not. Process information concerning propertiessuch as profile and critical dimensions of features present on andwithin the stacked structure can be extracted by employing ascatterometer. Using scatterometry, this information can be obtained bycomparing measured and calculated signatures relating to the stackedstructure. A signature may be defined as the phase and/or intensity ofthe light directed onto the surface of a wafer with phase and/orintensity signals of a complex reflected. and/or diffracted lightresulting from the incident light reflecting from and/or diffractingthrough the surface upon which the incident light was directed.

Conventional film metrology involves treating volumes which areessentially one-dimensional, that is composed of layers such assub-volumes separated by parallel planes. In scatterometry, theintensity and/or the phase of the reflected and/or diffracted lightchange according to properties of the stacked structure. Examples ofsuch properties include the roughness of the layers and thenon-planarity or non-parallelism of the subject plane(s) upon which thelight is directed.

Different combinations of such properties will have different effects onthe phase and/or intensity of the incident light resulting insubstantially unique signatures in the complex reflected and/ordiffracted light. Thus, by examining a database of calculated signaturesor model of calculated signatures, a determination can be madeconcerning the properties of the stacked structure. For instance, ameasured signature may be matched to a calculated signature, therebyyielding a measured profile of the stacked structure or a portionthereof. Such substantially unique signatures are produced by lightreflected from and/or refracted by different surfaces due, at least inpart, to the complex index of refraction of the surface onto which thelight is directed.

The complex index of refraction (N) can be computed by examining theindex of refraction (n) of the surface and an extinction coefficient(k). One such computation of the complex index of refraction can bedescribed by the equation N=n−jk, where j is an imaginary number.

Generally, the n and k values for a given surface layer may be measuredusing a spectroscopic ellipsometer (SE), which may be used, in part, togenerate such signature models in a semiconductor manufacturingendeavor. “Unpatterned wafer” means “an unpatterned portion of a wafer”.Optical instruments, e.g., an SE or a scatterometer, have a “spot size”of some size which defines the region where the instrument is sensitive.If a wafer has regions which are essentially uniform (“unpatterned”) aslarge as the spot size, those portions can be measured as “unpatterned”even though the wafer elsewhere has patterns, if the “spot” is placed onunpatterned on uniform regions. When exposed to a first incident lightof known intensity, wavelength and phase, a first layer with a firstchemical composition on a wafer can generate a first phase/intensitysignature. Similarly, when exposed to the first incident light of knownintensity, wavelength and phase, a second chemical composition on awafer can generate a second phase/intensity signature. For example, anitrided gate oxide layer with a first nitrogen concentration maygenerate a first signature while a nitrided gate oxide layer with asecond nitrogen concentration may generate a second signature.

Observed signatures can be combined with simulated and modeledsignatures to form the signal (signature) library. Simulation andmodeling can be employed to produce signatures against which measuredsignatures can be matched, for instance, using a profile matching serveror system. When phase/intensity signals are received from scatterometrydetecting components, the phase/intensity signals can be patternmatched, for example, to the library models of signals, in order todetermine whether the signals correspond to a stored signature.

Scatterometry may thus be advantageously employed in a semiconductordevice manufacturing or fabrication process, in order to measure certainprocess parameters associated with individual processing steps therein.For example, a lithography process step may involve patterning wafers inorder to create features thereon having certain critical dimensions(CDs), profiles, spacings, etc., wherein the overall quality of theresulting semiconductor device may depend on the accuracy of thelithography step. Scatterometry may be employed in order to verify suchdimensional process parameters, as well as other process conditions,such as overlay registration, and the like. Today, such model generationis typically done remotely from the process and scatterometer with whichthe models are ultimately to be employed. In order to setup ascatterometer for use with a new or changed process step, such modelsmust be obtained, along with recipes for performing one or more requiredmeasurements on processed wafers.

Obtaining models from such remote model generation sites sometimes takesdays, during which time wafers processed according to the new processstep cannot be measured using the scatterometer. In addition, thescatterometry measurement system may need to be trained in order toprogram new measurement recipes, during which time the scatterometercannot be used to measure production wafers. Thus, the generation and/orcreation of setup information such as models and recipes for use inmeasurement systems has heretofore resulted in significant processdown-time. Accordingly, there is a need for improved methods and systemsby which such setup down-time may be reduced or mitigated.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order toprovide a basic understanding of some aspects of the invention. Thissummary is not an extensive overview of the invention. It is intended toneither identify key or critical elements of the invention nor delineatethe scope of the invention. Rather, the sole purpose of this summary isto present some concepts of the invention in a simplified form as aprelude to the more detailed description that is presented hereinafter.

The present invention provides systems and methodologies for generatingsetup information for use in determining process parameters associatedwith semiconductor devices. The systems may be employed off-line, thatis, apart from an active, on-going semiconductor fabrication process, togenerate setup information for downloading to active-process measurementtools, such that the active-process tools may be kept running duringsetup information generation. In addition, the systems, though off-line,may be interconnected to the active fabrication process via a busconfiguration system, whereby measured and calculated informationrelating to a subject structure may be obtained by and shared with theactive fabrication process system as well as other measurement systemsand process tools as needed or desired. The bus configuration systemallows for information to be available to the various connectedmeasurement systems, tools and instruments almost immediately after therespective information becomes available. Furthermore, such systems maybe networked with integrated measurement or metrology tools employed bythe active fabrication process in order to improve the activefabrication process, such as setup information generation, defectclassification, data acquisition, rendering of data to a user,cross-calibration of measurement instruments, and the like.

The setup information generation systems comprise an off-linemeasurement instrument to measure a wafer, and a setup informationgenerator to generate models and/or recipes according to the wafermeasurement. The setup information generation system then provides thesetup information to an active process measurement system, such as anintegrated measurement tool or instrument, for use in measuringproduction wafers in a semiconductor manufacturing process.

According to an aspect of the present invention, a system is providedfor creating setup information for use in measuring process parametersassociated with semiconductor wafers in a semiconductor devicemanufacturing process, which comprises an off-line measurementinstrument adapted to measure a wafer and a setup information generator.The setup information generator is operatively connected to the off-linemeasurement instrument to create setup information according to ameasurement therefrom. The setup information is then provided to aprocess measurement system associated with the semiconductor devicemanufacturing process. The setup information can include recipes and/ormodels usable by the active process measurement system to measureprocess parameters associated with semiconductor wafers moving throughthe semiconductor device manufacturing process.

As used in the present invention, a recipe is a set of instructions fora measurement instrument comprising where to measure on the wafer,measurement system parameters for the physical measurement, andspecification of an algorithm or formula to convert the fundamentalphysical measurements into useful information. For example, for areflectometer measurement instrument, the recipe may compriseinformation about the layout of the wafer including die size andlocation, which dies on the wafer to measure, one or more sites withinthe die at which to measure (e.g., one or more sites corresponding tostructures in the die), pattern recognition parameters to identify andlocate structures in the die, length of time to integrate over formeasuring reflected intensities, wavelengths of light at which to reportmeasured intensities, an algorithm or mathematical formula based on amodel that comprises a stack of thin films at the measurement location,specification of which parameters are known and which are to bemeasured, and the like. Other information may also be included in therecipe, depending on the applicable measurement instrument andrequirements of the user.

A model, according to the present invention, can be described as aphysical structure (e.g., wafer or stack of film layers) having a set ofboundaries or parameters associated therewith. For example, Model X1involves a structure B with a first set of parameters (e.g., 20variables), whereby Model X1 yields an optical response B1 which maydefine a particular point in data space. Model X2 involves the structureB but with a second set of parameters, which yield an optical responseB2. The second set of parameters may include a variation of at least oneof the 20 variables in the first set of parameters. A spectrum can beproduced from each optical response, and the spectra taken from ModelsX1 to Xn can be stored in a library. Spectra may be derived from eitherreal wafer samples or from theoretical calculations.

Another aspect of the invention provides a method of generating setupinformation for measurement of process parameters associated with anactive process measurement system in a semiconductor devicemanufacturing process. This aspect of the invention comprises performinga measurement of a wafer using an off-line measurement instrument,generating setup information according to the measurement using a setupinformation generator, and providing the setup information from thesetup information generator to the process measurement system using anetwork. The measurement can comprise measuring an optical constantassociated with a layer on the wafer using a spectroscopic ellipsometer,and the setup information generation may comprise generating a signaturematching model for use in association with an optical scatterometeremploying the optical constant from the spectroscopic ellipsometer.

According to yet another aspect of the invention, a system is providedfor generating a model for use in matching measured spectra from anoptical scatterometer with performance parameters associated with aprocessed semiconductor wafer. The system comprises a spectroscopicellipsometer (SE) operative to measure optical constants associated withunpatterned portions of wafers and to provide a file of informationrelating to film parameters and process parameters associated with theunpatterned wafers and calibration information associated with the SE.The system further comprises a model generator receiving the file fromthe SE and operative to generate a model usable by a process measurementsystem according to the file, film and process parameters, and metrologyinstrument parameters associated with the process measurement system. Inaddition, the system comprises means for transferring the model to theprocess measurement system, such as a network.

Another aspect of the invention provides a system for measuring processparameters associated with semiconductor products in a semiconductormanufacturing process. The system comprises a first measurementinstrument integrated into a process tool in the manufacturing processand a stand-alone measurement system having a second measurementinstrument similar to the first measurement instrument. The stand-alonemeasurement system is operative to perform at least one support servicefor the first measurement instrument using the second measurementinstrument, such as generation of setup information (e.g., measurementrecipes, models, or the like), defect classification, data acquisition,rendering data to a user, and cross-calibration. The system furthercomprises a network, such as a high-speed TCP/IP network, operativelyinterconnecting the first measurement instrument in the process toolwith the stand-alone measurement system, whereby information and datamay be transferred therebetween.

To the accomplishment of the foregoing and related ends, certainillustrative aspects of the invention are described herein in connectionwith the following description and the annexed drawings. These aspectsare indicative, however, of but a few of the various ways in which theprinciples of the invention may be employed and the present invention isintended to include all such aspects and their equivalents. Otheradvantages and novel features of the invention will become apparent fromthe following detailed description of the invention when considered inconjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating an exemplary system forcreating setup information in which one or more aspects of the presentinvention may be implemented;

FIG. 2 is a schematic diagram illustrating an exemplary stand-alonesystem for generating setup information in accordance with theinvention;

FIG. 3 is a schematic diagram further illustrating the system of FIG. 2;

FIG. 4 is a schematic diagram illustrating the stand-alone system ofFIGS. 2 and 3 providing setup information to a process measurementsystem in accordance with another aspect of the invention;

FIG. 5 is a schematic diagram illustrating another exemplary stand-alonesystem providing setup information to an integrated metrology system ina process tool;

FIG. 6 is a schematic diagram illustrating a stand-alone system forcreating setup information networked with several integrated metrologysystems and an APC server via a high speed network in a semiconductordevice manufacturing process;

FIG. 7 is a schematic diagram illustrating a stand-alone metrologysystem receiving models from an associated local model generator inaccordance with another aspect of the invention;

FIG. 8 is a schematic diagram illustrating an exemplary stand-alonemetrology system with integral ellipsometer and model generator inaccordance with the invention;

FIG. 9 is a schematic diagram illustrating a stand-alone metrologycluster with associated defect classification and model generationsystems networked to an integrated metrology system in a lithographyprocess tool in accordance with another aspect of the invention;

FIG. 10 is a schematic diagram illustrating a portion of a manufacturingprocess having two process clusters with integrated metrology systems inprocess tools, and having networked stand-alone metrology clustersservicing the integrated metrology systems within the process clusters;and

FIG. 11 is a flow diagram illustrating an exemplary method of generatingsetup information in accordance with another aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The various aspects of the present invention will now be described withreference to the drawings, wherein like reference numerals are used torefer to like elements throughout. The invention provides systems andmethods for generating setup information, such as models and/or recipes,for use measuring process parameters associated with semiconductordevices. In one aspect of the invention, models and/or recipes aregenerated in a stand-alone measurement system networked to one or morein-process measurement systems. The stand-alone system may thus be usedto perform setup type operations (e.g., model and/or recipe generation)in off-line fashion for subsequent downloading of such setup informationto in-line process measurement systems. The invention may thus reduce ormitigate down-time associated with such setup operations.

Referring initially to FIG. 1, an exemplary system 2 is illustrated forcreating setup information 4 in association with a semiconductor devicemanufacturing process 6, in which one or more aspects of the presentinvention may be implemented. The setup information 4 can be distributedto and employed by an active process measurement system 8 in measuringprocess parameters (e.g., CDs, profiles, overlay registration, and otherprocess parameters) associated with semiconductor wafers 10 beingprocessed by an integrated process tool 12 (e.g., lithography station orother process tool) in the manufacturing process 6. The system 2comprises an off-line measurement instrument 20, such as a spectroscopicellipsometer (SE), scanning electron microscope (SEM), atomic forcemicroscope (AFM), scatterometer, or other type of measurementinstrument, which is adapted to measure a wafer 22. For instance, theinstrument 20 may be an ellipsometer operative to measure opticalconstants such as n and k values associated with unpatterned portions ofthe wafer 22. The system 2 further comprises a setup informationgenerator 30 operatively associated with the instrument 20 to create thesetup information 4 according to a measurement 32 therefrom, and toprovide the setup information 4 to the active process measurement system8.

The setup information 4 can include any type of setup information usableby the active process measurement system 8, such as for example, arecipe 40 and/or a model 50. For instance, the model 50 may refer to aplurality of models (e.g., one or more models) such as Models X1 to Xn.Each Model X1 to Xn has the same physical structure but each has adifferent set of parameters associated therewith. The parameters mayinclude one or more variables and each set of parameters may vary by asfew as one variable. A calculated spectrum can be generated from eachmodel which corresponds to a light-scattering pattern relating to thephysical structure of the model and its given a set of parameters.

The calculated spectra derived from Models X1 to Xn may also be referredto as calculated or theoretical signatures and stored in a signaturelibrary (e.g., intensity/phase signatures). The active processmeasurement system 8 compares a spectrum of a sample or unknown wafer10, which can be generated by a scatterometer, with signature library tofind the closest match. This may be referred to as signature matching.Once the closest match is selected, the data associated with the closestmatch (e.g., stored signature of Model X5) is analyzed in order to “see”what structure was just measured. Additional models can then begenerated by adjusting the parameters of Model X5 in order to obtain aneven closer match. The measurement system 8 may make a determinationconcerning the properties of the surface of the wafer 10, such as thesize, roughness, planarity, or spacing of features (e.g., lines)patterned thereon by the integrated process tool 12. Thus, for example,measured signatures produced by light reflected from and/or refracted bydifferent surfaces in the wafers 10 which are due, at least in part, tothe complex index of refraction of the surface thereof, may be comparedwith theoretical signatures derived from the model 50, whereby a processparameter (e.g., CD, profile, overlay registration, or other parameter)may be ascertained by the measurement system 8, for example, usingsignature matching or other type of correlation technique. In thisregard, the measurement 32 from the off-line instrument 20 can includethe index of refraction (n) of the surface of the unpatterned wafer 22,as well as an extinction coefficient (k).

The signature library can also be constructed in the setup informationgenerator 30 from measured signatures of real samples such as theunpatterned wafer 22 and/or from calculated signatures generated bymodeling and simulation. Measured signatures can be combined withcalculated signatures to form the signature library. Thus, simulationand modeling can be employed to produce signatures in the model 50against which measured signatures can be matched in the processmeasurement system 8. It will be appreciated in this regard, that suchsimulation, modeling and/or measured signatures can be stored in alibrary (not shown) in the measurement system 8, wherein the library caninclude many such measured and/or calculated signatures of known andunknown real samples. Thus, when the phase/intensity signals arereceived from scatterometry-detecting components in the system 8, thesecan be compared to or otherwise correlated with the closest matchingsignature stored in the library.

In addition, the setup information may be transferred by any means, suchas wherein the setup information generator 30 comprises a networkinterface (not shown) operative to transfer the setup information 4 tothe process measurement system 8 via a network or bus configuration tofacilitate immediate sharing of information between the various off-lineand active measurement systems, instruments, and process tools, asillustrated and described in greater detail hereinafter. The system 2,thus allows for off-line setup operations to be performed thereon, whilethe active process measurement system 8 may continue to actively measurewafers 10 with the integrated process tool 12. In this manner, theinvention may be advantageously employed to mitigate down-timeassociated with conventional setup information creation techniques.

According to another aspect of the invention, a setup informationcreation system may be implemented as a stand-alone automated system orcluster 102 as illustrated in FIG. 2, comprising a cluster ofmeasurement instruments or systems 110, 112, and 114 for measuringwafers 4. The cluster 102 may be advantageously employed for measuringprocess parameters (e.g., overlay registration, photoresist layerdefects, feature sizes, spacing between features, particle defects,chemical defects, film or layer roughness, and the like) associated withwafers 104 in a semiconductor fabrication process, as well as forgeneration of setup information for transferring to other measurementsystems or measurement system clusters. The cluster 102 comprises aplurality of measurement systems 110, 112, and 114 having measurementinstruments (not shown) associated therewith. For example, the systems110 and 112 can include scanning electron microscopes (SEMs), atomicforce microscopes (AFMs), scatterometers, or other measurementinstruments adapted to measure process parameters associated withprocessed semiconductor wafers 104, and the measurement system 114 is aspectroscopic ellipsometer (SE) in the exemplary cluster 102.

The exemplary cluster 102 further comprises a wafer transfer system 120,such as a robot or other automated wafer translation apparatus, whichreceives wafers 104 via an unloader station 122 which unloads wafers 104from a cassette 124 or other wafer carrying device. Alternatively or incombination, wafers 104 can be provided to the wafer transfer system 120(e.g., or individually to the measurement systems 110, 112, and/or 114)manually. The wafer transfer system 120 operates to selectively providewafers 104 to one or more of the measurement systems 110, 112, and/or114 according to a measurement system selection criteria, such as wafermeasurement throughput, measurement system accuracycapabilities,,measurement system availability, or other factors. One ormore process parameters (e.g., CDs, profiles, overlay registration, orthe like) are then measured and/or inspected in order to verify properprocessing of the wafers and/or to detect defects or errors in thefabrication process. Furthermore, the measurement(s) from one or more ofthe measurement systems 110, 112, and/or 114 may be employed in order togenerate setup information (e.g., recipes and/or models) for use in thecluster 102 or for provision to other measurement systems.

The exemplary cluster system 102 further comprises a server 130 having arecipe generator 131, a model generator 132, an external networkinterface 133 for transferring setup information (e.g., from the recipegenerator 131 and/or the model generator 132) to other measurementsystems or instruments via an external network (not shown), ameasurement system selection logic 134, and calibration information 136therein, as well as a user interface 138. The user interface 138 may beused to obtain user information in generating recipes for measurement ofprocess parameters in a process measurement system, as well as forrendering measurement data, statistics, or other report information fromthe cluster 102 to a user. For example, the server 130 may gathermeasurement data from the measurement systems 110, 112, and/or 114, aswell as from other networked measurement systems or instruments (e.g.,via the external network interface 133), which may then be formatted andpresented to a user via the interface 138. The measurement systems 110,112, and 114, as well as the unloader station 122, the wafer transfersystem 120, and the server 130 are networked together via a network 140internal to the cluster 102, whereby measurement information,measurement system selection information, calibration information 136,and other control information and data may be shared between the variouscomponents of the measurement system cluster 102.

Once the appropriate process parameters associated with the wafers 104have been measured via the measurement systems 110, 112, and/or 114, thewafer transfer system 120 provides the wafers 104 to a loader station142 which loads the wafers into outgoing wafer cassettes 124 fortransfer to other systems in the fabrication process, such as adownstream process tool (not shown). One skilled in the art willrecognize that the loader and unloader stations may be physically thesame device, and that the incoming and outgoing cassettes may be thesame. The cluster 102 preferably further comprises an optical characterrecognition (OCR) system 144 providing a wafer identification (notshown) to the measurement system selection logic component 134 via thenetwork 140, whereby the component 134 may make an appropriate selectionof measurement system(s) 110, 112, and/or 114 to be used to measure orinspect the wafer 104. Although the exemplary cluster 102 identifies thewafers 104 using the OCR system 144, other techniques may be used toidentify the wafers 104, such as for example, location within thecassette 124, or other methods as are known. It will be appreciated,however, that where lot code information, date codes, and the like areprinted or stamped directly on the wafers 104, the OCR system 144 canadvantageously reduce the likelihood of incorrect wafer identification.

The measurement system selection logic component 134 in the server 130provides a measurement system selection to the wafer transfer system 120according to one or more selection criteria, wherein the wafer transfersystem 120 provides the wafers 104 to at least one of the measurementsystems 110, 112, and/or 114 according to the measurement systemselection. For example, the measurement system selection criteria caninclude capabilities requirements information associated with the wafer104, as well as capability information, availability information, andthroughput information associated with the measurement systems 110, 112,and 114. The selection moreover, may be made according to a desiredsequencing of measurements in the systems 110, 112, and/or 114, forexample, where the spectroscopic ellipsometer 114 is employed to measureoptical constants or the like associated with an unpatterned wafer 104,which constants are then provided to the model generator 132 in theserver 130 via the internal network 140, in order to generate a model.

The capabilities information may thus be derived according to the waferidentification from the OCR system 144, and may comprise informationindicating the type of feature(s) or dimension(s) to be measured in thesystem 102, as well as the required accuracy for the measurement(s). Themeasurement system selection from the logic component 134 may furthertake into account the measurement capabilities of the variousmeasurement systems 110, 112, and/or 114. For example, one or more ofthe systems 110, 112, and/or 114 may be capable of performing a givenmeasurement within the required accuracy, while others may not. Inaddition, the respective systems 110, 112, and/or 114 can each havedifferent throughput capabilities. For instance, a SEM instrument may beable to measure 130 wafers per hour (wph), a scatterometer may measureup to 150 wph, and a spectroscopic ellipsometer may measure 75 to 80wph. In selecting a measurement system to perform a given measurementtask, therefore, the measurement system selection logic component 134may advantageously select the system which can provide the highestthroughput, within the required measurement capabilities for themeasurement.

In this regard, the selection logic component 134 may also considerwhich systems 110, 112, and/or 114 are currently available in schedulingthe, transfer of wafers 104 via the transfer system 120. Thus, themeasurement system selection logic component 34 provides the selectionindicating a selected measurement system 110, 112, or 114 havingcapabilities required for the wafer 104 according to the capabilitiesrequirements information (e.g., obtained or derived from the waferidentification via the OCR system 144) and the measurement systemcapability information. Furthermore, the selection may reflect themeasurement system having the highest throughput with the capabilitiesrequired for the wafer 104 according to the measurement systemavailability information and the throughput information.

As the various measurement systems 110, 112, and 114 are interconnectedin the cluster 102, and may share information via the network 140, thesystems 110, 112, and/or 114 may be cross-calibrated. In this regard,the calibration information 136 in the server 130 may be shared betweenthe various systems 110, 112, and 114, whereby the measurements made byone measurement instrument in the systems 110, 112, or 114, arecomparable to those made by another such instrument. In addition, suchcalibration may be provided to other measurement systems via theexternal network interface 133, for example, whereby cross-calibrationmay be achieved between measurement instruments 110, 112, 114, and othermeasurement systems outside the cluster system 102. The exemplarycluster system 102 thus provides significant advantages overconventional stand-alone measurement systems with respect tocross-calibration as well as in reducing excess transferring of thewafers 104 between such stand-alone measurement stations in afabrication process.

Information may be provided to an upstream (e.g., or downstream) processtool (e.g., photo-resist track, stepper, or the like), which can employsuch information as process feedback, whereby on-line closed-loopprocess control can be achieved, for example, wherein the process toolperforms fabrication processing steps according to the measurement datain order to mitigate defects in processed wafers 104. Alternatively orin combination, the measurement (e.g., and/or defect detection)information may be provided to an advanced process control (APC) system(not shown), which in turn may provide process adjustments to suchprocess tools in feedback and/or feed forward fashion. In this regard,it will be appreciated that the reduction in transfer time resultingfrom clustering of multiple measurement systems 110, 112, and 114 into asingle system 102, as well as the selective employment of appropriatemeasurement systems based at least in part on throughput and/oravailability information, may be used to mitigate down-time of relatedprocess tools, whereby real-time or near real-time measurement and/ordefect detection may be achieved with little or no fabrication processdown-time, in accordance with the present invention. Moreover, theexemplary measurement cluster 102 may also be integrated with a processtool, as illustrated further hereinafter, which operates to perform oneor more fabrication processing steps on the wafers 104 and to providethe processed wafers 104 to the wafer transfer system 120.

Referring also to FIG. 3, further details of the exemplary system 102are illustrated, wherein the system 102 may be advantageously employedto perform model generation to create one or more models Z1 to Zn 150using the model generator 132. An unpatterned wafer 152 is provided tothe SE 114 (e.g., manually or via wafer transfer system 120), togetherwith film and process parameters 154 associated with the processing ofthe wafer 152, and calibration information 156 from the server 130. The.ellipsometer 114 is then employed to measure the wafer 152 for providingn, k files 158 to the server 130 via the internal network 140, forexample, including the refractive index n and extinction coefficient k.The files 158 are then provided to the model generator 132 along withfilm and process parameters 154 and measurement instrument parameters160, which the model generator 132 uses to generate the model 150. Themodel 150, in turn, may be stored in a library 162 having N such models164 through 166. A signature matching component 170 in the server 130thereafter may receive a measured spectrum 172 (or spectra) associatedwith a measured wafer 104 from a measurement system 110 (e.g., whereinsystem 110 can include a scatterometer), wherein the component 170compares or correlates the measured spectra 172 to determine aperformance parameter 176 (e.g., profiles, CDs, or the like) associatedwith the wafer 104.

The cluster system 102 may alternatively or in combination be used togenerate a recipe 180 via the recipe generator 131, for use in makingwafer measurements using the measurement system 110. For instance, auser may train the system 102 via the user interface 138 for patternrecognition, selection of wafer sites to be measured, entry ofacceptance limits, setting of alarm conditions, setting control limitsfor measured data, formatting for displaying or reporting measured dataand/or statistics, destination to which measured data is to be sent, andthe like. This recipe 180 may thereafter be used in measuring one ormore wafers 104 using measurement systems 110, 112, and/or 114 in thecluster 102, and/or may be transferred to other measurement systems viathe external network interface 133 (e.g., FIG. 2). The exemplarymeasurement system cluster 102 may thus provide significant advantagesin performing setup operations such as model and/or recipe creation,wherein the setup tasks may be done in an off-line fashion while processmeasurement systems are used for measuring production wafers, therebymitigating down-time associated with prior setup information generationtechniques.

Referring now to FIG. 4, the stand-alone system 102 can be used toprovide setup information, such as recipe 180 and/or model Z1 to Zn 150,to a separate and possibly remote process measurement system 182receiving wafers 104 from a process tool 184 (e.g., lithography stationor other process tool related to semiconductor device fabrication) inaccordance with another aspect of the invention. The systems 102 and 182may be operative to communicate with one another via a network (notshown) as illustrated and described in greater detail hereinafter, suchas a high-speed TCP/IP network. The process measurement system 182,moreover, can be of any type, including but not limited to anotherstand-alone cluster, an integrated metrology system within a processtool and having one or more measurement instruments or systems therein,or other apparatus operative to measure one or more process parametersassociated with semiconductor wafers.

The process measurement system 182 comprises one or more measurementsystems 186, such as a scatterometer providing measured spectra 188 to asignature matching server 190 with a library 192 of models. Thesignature matching server 190 in the process measurement system 182correlates the measured spectra with the models in the library 192 inorder to determine one or more process parameters 194, such as profiles,CDs, overlay registration, or the like. The setup information generationsystem 102 may advantageously create one or more models 150 for transferto the process measurement system 182, whereby the model 150 may beadded to the library 192 in the signature matching server 190, where itwill be available for use in the process measurement system 182 as theneed arises in the course of processing of wafers 104 using the processtool 184. Alternatively or in combination, the setup informationgeneration system 102 may be used to generate a measurement recipe 180,which may also be provided to the measurement system 186 in the processmeasurement system 182. Such recipes 180 and/or models 150 can also bereplicated from a database (not shown) in the server 130 to any numberof networked process measurement systems or instruments, whereby thestand-alone system 102 may operate as a centralized data store for suchsetup information.

The database may also contain information to facilitate conversion ofthe measured information collected by an instrument into useableinformation about the process state of the wafer 104. For example,partial results of lengthy mathematical calculations and algorithms maybe stored in a database for later, accelerated use. Measurement systemsand metrology clusters described throughout FIGS. 1-4 above and FIGS.5-11 below can generate databases to facilitate the determination andidentification of wafer structures in accordance with the presentinvention. For further description of the database approach, pendingU.S. application Ser. No. 09/927,177 (Publication No. 2002/0038196 A1)entitled “Database Interpolation Method For Optical Measurement ofDiffractive Microstructures” is hereby incorporated by reference.

Referring now to FIG. 5, another exemplary system 202 is illustrated forcreating setup information in accordance with the invention. As with theexemplary system 102 of FIGS. 2-4, the system 202 comprises a pluralityof measurement instruments clustered together, with a robot 204 totransfer wafers (not shown) between one or more of the instruments andloading and/or unloading stations 206 and 208, respectively. The systemcomprises a scanning electron microscope (CD-SEM) 210, an opticalscatterometer 212, and a spectroscopic ellipsometer (SE) 214 located soas to allow transfer of wafers thereto from the robot 204. It should beappreciated that optical scatterometer 212 may comprise spectroscopicellipsometer 214. In addition, the optical scatterometer 212 may alsocomprise a reflectometer (not shown).

The system 202 also comprises a model generator 218 and can be operatedin similar fashion to the system 102 with respect to generating models216. For instance, the SE 214 may be employed to measure an unpatternedwafer (not shown), and may provide one or more optical constants (e.g.,n, k files) to the model generator 218, which in turn provides one ormore model files 216 to the scatterometer 212. The scatterometer 212includes a signature matching system (not shown), which may be used tomatch measured spectra from production wafers (not shown) withtheoretical signatures from the model files 216 in order to measureand/or determine one or more process parameters associated therewith.Alternatively or in combination, the model files 216 may be provided toan integrated metrology system 230 in a process tool 232 in accordancewith another aspect of the invention.

The system 202 may also be used to generate measurement recipes for usein association with one or more of the measurement instruments 210, 212,and/or 214 therein. Such recipes and model files 220 can furthermore betransferred to a process measurement system, such as the integratedmetrology system 230 in the process tool 232. The cluster system 202 mayalso be provided with data 234, such as measurement data, statistics,etc., from the process tool 232 and/or from the integrated metrologysystem 230 therein, whereby a user (not shown) may access such data(e.g., together with data from other networked process measurementsystems associated with the system 202) from a centralized location atthe cluster 202, without having to visit each such process measurementsystem individually. In this regard, the system 202 may comprise a userinterface (not shown) allowing the user to interface therewith forobtaining such data, generating measurement recipes, and otheroperations. It will farther be appreciated in this regard, that theprovision of the system 202 allowing such access to the associatedprocess measurements (e.g., from the integrated metrology system 230)may advantageously eliminate the need for such user interfaces at theprocess measurement systems.

Referring now to FIG. 6, a portion of an exemplary semiconductor devicemanufacturing process 302 is illustrated, wherein semiconductor wafers304 are successively processed by process tools 310, 312, 314, and 316.The process tools 310, 312, 314, and 316 have integrated measurement ormetrology systems or instruments 320, 322, 324, and 326 integratedtherein, respectively, for measuring one or more process parametersassociated with the wafers 304, such as CDs, overlay registration,profiles, or the like, in order to ascertain the quality of the wafers304, the accuracy of the process tools 310, 312, 314, and/or 316, orotherwise to verify proper processing of the wafers 304 in the process302. The process tools 310, 312, 314, and 316 are connected to a factorynetwork 320 for communication with each other as well as with anadvanced process control (APC) server 322, which can provide control ofthe tools 310, 312, 314, and/or 316, data acquisition therefrom, datareview and analysis functions, network management functions, as well asproviding a data store for various processing recipes used by the tools310, 312, 314, and/or 316.

The integrated measurement systems 320, 322, 324, and 326 are networkedtogether via a high-speed network, such as a TCP/IP network 330 in orderto communicate with each other and with a stand-alone measurement system340 having one or more measurement systems 342 integrated therein. Thestandalone system 340 is operable to generate (e.g., and/or edit)measurement recipes usable by the process measurement systems 320, 322,324, and 326, as well as to create models for use by the measurementsystems in the process 302, in a manner similar to the systems describedabove. In this regard, the system 340 includes measurement instruments342 of the same or similar type as those for which the system 340provides such support services. Thus, where the integrated measurementsystems 320, 322, 324, and 326 each comprise a CD-SEM and ascatterometer, the stand-alone system 340 also includes a CD-SEM and ascatterometer, thereby allowing the stand-alone system 340 to be usedfor off-line generation or creation of setup information (e.g., recipesand/or models) for use in the integrated measurement systems 320, 322,324, and/or 326.

In addition, the stand-alone system 340 may be adapted to providediagnostics services to the process 302, for example, whereinmeasurement data from- one or more of the measurement systems 320, 322,324, and 326 are analyzed in order to identify process anomalies ordefects in the wafers 304. Furthermore, the system 340 may include adata store for measurement recipes and models used by the measurementsystems 320, 322, 324, and 326, as well as for calibration information(not shown) related thereto. Thus, the standalone system 340 providesfor cross-calibration of the various measurement systems 320, 322, 324,and/or 326, as well as the measurement system 342 integrated therein.

Referring now to FIG. 7, another implementation of the inventioncomprises a stand-alone metrology system 404 receiving models from anon-site local model generator 406 associated therewith in asemiconductor device manufacturing process 402. The process 402comprises process tools 410, 412, and 414 networked to each other aswell as to an APC server 416 via a factory network 418. The processtools comprise integrated measurement systems or instruments (e.g.,which may be clusters of instruments) 420, 422, and 424, respectively,operative to measure process parameters associated with wafers (notshown) processed by the tools 410, 412, and/or 414 in a manner similarto the systems described hereinabove. The measurement systems 420, 422,and 424 are networked to each other as well as to the stand-alone system404 via a high-speed network 420 for transfer of informationtherebetween. For instance, the network 420 advantageously provides fortransfer of setup information (e.g., models and/or recipes) 422 from thestand-alone system 404 to one or more of the measurement systems 420,422, and 424 in accordance with the present invention. In addition, data426 may be transferred from one or more of the measurement systems 420,422, and 424 to the stand-alone system 404 via the network 420.

The stand-alone system may be employed to generate models 428 using anassociated model generator 406 and an ellipsometer 430 providing n,kfiles 432 thereto, and may but need not include an associated profileand/or signature matching server (not shown). The model generator 406can include one or more servers or computer systems, which receive then,k files 432 and generate the models 428 in accordance therewith, forexample, wherein an unpatterned wafer (not shown) is measured using theellipsometer 430 in order to produce the n,k files 432. Such models 428and recipes 422 may then be uploaded to one or more process measurementsystems 420, 422, and/or 424 via the network 420 for use thereby inorder to measure one or more process parameters associated with wafersin the process 402.

Another implementation of the present invention is illustrated in FIG.8, wherein an exemplary semiconductor wafer fabrication process 452comprises process tools 460, 462, and 464 networked together with an APCserver 454 via a factory network 456, wherein the process tools 460,462, and 464 respectively comprise integrated process measurementsystems or tools 470, 472, and 474 networked via a high-speed network458, wherein the APC server 454 can also interact with the network 458.A stand-alone measurement system 480 with interfaces to both networks456 and 458 includes one or more integrated metrology or measurementsystems or instruments 482 in similar fashion to the stand-alone system102 illustrated and described above with respect to FIGS. 2-4, as wellas an integrated model generator 484.

In addition to measurement systems or instruments of the same or similartype as the systems 470, 472, and 474 in the process tools 460, 462, and464, respectively, the integrated measurement system 482 in thestand-alone system 480 comprises an ellipsometer adapted to measureunpatterned wafers (not shown) in order to provide optical constants(e.g., n,k files) to the model generator 484. Models and/or measurementrecipes 490 may then be transferred to one or more of the integratedprocess measurement systems 470, 472, and/or 474 via the network 458,and data 492 may be obtained therefrom by the stand-alone system 480.Moreover, such measurement recipes, models, and other setup informationmay be replicated into a data store in the APC server 454 after receiptin the measurement systems 470, 472, and/or 474, where such replicationmay be performed via either of the networks 456 or 458.

Referring now to FIG. 9, one or more aspects of the present inventionmay be applied to a lithography track type process tool 504 as part of asemiconductor device fabrication or manufacturing process 502. Althoughillustrated and described herein with respect to a lithography processtool, it will be appreciated that the invention finds application inassociation with any processing steps in such a manufacturing process,and that such applications are deemed to fall within the scope of theinvention. The process tool 504 includes components (not shown) forperforming one or more lithography steps to wafers in the process 502,as are known. In addition, the tool 504 comprises an integrated opticalscatterometer measurement instrument 506 for measuring processparameters such as CDs, overlay registration, film thicknesses,profiles, or the like. The tool 504 further includes an inspectioncomponent 508, whereat wafers may be inspected for defects andparticulate matter. The scatterometer 506 and the inspection component508 are networked via a track network 510 together with a trackcontroller 512, which provides for controlled operation of the tool 504.

The track controller 512, inspection component 508, and thescatterometer 506 are operatively connected with a fabrication network520 along with an APC controller 522, which operates in similar fashionto the APC servers illustrated and described above. The measurement andinspection systems 506 and 508 are further networked with a stand-alonemetrology cluster 530 having an associated defect classification system532 and library or model generator system 534. The cluster 530 includesa scatterometer (not shown) similar or identical to the scatterometer506 in the track tool 504, whereby the cluster may be used to createmeasurement recipes therefor while the scatterometer 506 is otherwiseavailable for measuring wafers in the process 502, which recipes maythen be transferred to the process scatterometer 506. Once received inthe scatterometer 506, such recipes may then be replicated to ameasurement recipe data store (not shown) in the APC controller 522.

The cluster 530 further comprises a spectroscopic ellipsometer (notshown) cooperating with the model generator 534, whereby models may begenerated in the cluster 530 for uploading to and use by the processscatterometer 506. Data from one or both of the process scatterometer506 and/or the inspection component 508 may be transferred to thecluster 530, for analysis, detection, and/or diagnosis of one or moredefects using the defect classification system 532. It will beappreciated that the various functions described for the cluster 530, aswell as the other setup information creation systems and devices hereinmay be implemented in software executing on a server or other computersystem or groups of such systems, or may be implemented in hardware orcombinations of hardware and software, within the scope of the presentinvention. In this regard, the defect classification systems 532 and/orthe model generator system 534 may comprise software in a server in thecluster 530, or may reside in individual servers within the cluster 530,or in other such integrated or associated implementations.

Data from the integrated metrology tool 506 can be advantageouslyemployed in a variety of ways in order to identify proper performance ofthe track process tool 504. For instance, critical dimension (CD) datathat is collected by an integrated metrology system such as thescatterometer 506 in the track 504 can be analyzed with the datacollected from a variety of other devices in order to deconvolve thevarious sources of CD uniformity. Such analysis may be performed ineither of the stand-alone cluster 530 and/or the APC controller 522. Asone example, the temperature uniformity of each bake plate (not shown)in the track 504 can be mapped using a sensor wafer such as thoseavailable from Sensarray or On Wafer Technologies. When the CD is mappedusing an integrated CD tool such as scatterometer 506, this uniformityis a function of the bake-plate uniformity as well stepper doseuniformity and possibly resist thickness uniformity. The integratedmeasurement instrument 506 may be used to measure two of these threeprocess parameters associated with a wafer, and the data analysis (e.g.,in the cluster 530 and/or the APC controller 522) may comprise deducingthe stepper dose uniformity from measurement data for the bake plateuniformity and resist thickness. Thus, data from the integratedmetrology tool 506 can be used for advanced process control (APC)functions.

Referring now to FIG. 10, another aspect of the present inventionprovides for integration of one or more measurement instruments orsystems in a process tool, where the measurement system or systems arenetworked to a stand-alone measurement system with a similar oridentical measurement instrument. The stand-alone measurement system canthus provide support services for the integrated instrument(s), such asgeneration of setup information (e.g., measurement recipes, models, orthe like), defect classification, data acquisition and reporting forrendering to a user, cross-calibration, and the like. A semiconductordevice manufacturing process 602 is illustrated in FIG. 10, having twoprocess clusters, process cluster A and process cluster B, each processcluster having like process tools associated therewith.

Process cluster A comprises three process tools 610, 612, and 614 oftype “A”, for example, such as lithography tools. The type A tools 610,612, and 614 in process cluster A each comprise integrated measurementinstruments of types M1 and M2, for instance, wherein M1 may be a CD-SEMtype measurement instrument, and M2 may be an optical scatterometertype. Many forms of measurement instrument integration are contemplatedwithin the present invention, including but not limited to physicalintegration of such instruments within a process tool enclosure,attachment thereto, or other integration techniques. In addition tophysical integration, the integrated measurement instruments or systemsmay be interconnected with such process tools so as to allowcommunication of information and/or data therebetween. The measurementinstruments M1 and M2 integrated into the type A process tools 610, 612,and 614 are selected so as to accommodate measurements associated withthe wafer processing performed by the type A process tools 610, 612, and614.

Similarly, process cluster B comprises three process tools 620, 622, and624 of type “B”, each having process measurement instruments or systemsof type M4 and M5 selected according to the processing performed by thetype B tools 620, 622, and 624. For instance, the type B process tools620, 622, and 624 may comprise etch tools. The integrated measurementinstruments M1, M2, M4, and/or M5 may comprise individual measurementinstruments, or alternatively may comprise clusters of similar ordissimilar measurement instruments within the scope of the presentinvention. The process tools 610, 612, 614, 620, 622, and 624 areoperatively interconnected with each other and with an APC controller630 via a factory network 632 for communication of information and/ordata therebetween. For instance, the APC controller may provide controlinformation, process recipes, calibration information, or the like tothe tools 610, 612, 614, 620, 622, and 624, and may receive measurementinformation or other information therefrom.

Stand-alone measurement system or metrology clusters 640 and 650 areoperatively associated with the integrated measurement instruments-ofthe process tools in process clusters A and B via local cluster networks660 and 670, respectively, as well as via the factory network 632. Thestand-alone cluster 640 comprises measurement instruments (e.g., orclusters) M1 and M2 which are of the same or similar type (e.g., CD-SEMand scatterometer, respectively) as the instruments M1, and M2integrated with the process tools 610, 612, and 614 of process clusterA, such that the metrology cluster 640 may provide one or more supportservices to the integrated measurement instruments or systems within theprocess cluster A.

In addition, the stand-alone cluster 640 includes a measurementinstrument of type M3, and a wafer transfer system or robot 642operative to selectively provide wafers 680 to one or more of theinstruments M1, M2, and/or M3 therein. For instance, the M3 instrumentcan be a spectroscopic ellipsometer operative to measure opticalconstants associated with the wafers 680, whereby a model generator (notshown) in the cluster 640 may create models for use in thescatterometers M1 of the process tools 610, 612, and/or 614 of theprocess cluster A, in a manner similar to that described above withrespect to FIG. 3. Alternatively or in addition, the cluster 640 mayperform other support services for the integrated metrology devices inthe tools 610, 612, and/or 614, including but not limited to generationof other setup information (e.g., measurement recipe creation), defectclassification, data acquisition, rendering data to a user,cross-calibration, or the like.

Similarly, a stand-alone measurement system cluster 650 is operativelyassociated with the measurement instruments M4 and M5 in the processtools 620, 622, and 624 of process cluster B via another local network670, and well as via the factory network 632. The cluster B 650comprises measurement instruments M4 and M5 of the same or similar typeas the instruments M4 and M5 integrated in the process tools 620, 622,and 624, whereby support services may be provided to the integratedinstruments using the stand-alone system 650, such as generation ofsetup information (e.g., model creation, measurement recipe creation,etc.), defect classification, data acquisition, rendering data to auser, cross-calibration, or the like. Also, the cluster system 650comprises a robot 652 operational in a fashion similar to the robot 642of cluster 640.

Referring now to FIG. 11, another aspect of the invention providesmethods for generating setup information for measurement of processparameters associated with a process measurement system in asemiconductor device manufacturing process. The invention comprisesperforming a measurement of a wafer using an off-line measurementinstrument, generating setup information according to the measurementusing a setup information generator, and providing the setup informationfrom the setup information generator to the process measurement systemusing a network.

An exemplary method 700 is illustrated in accordance with the presentinvention beginning at 702. Although the exemplary method 700 isillustrated and described herein as a series of blocks representative ofvarious events and/or acts, the present invention is not limited by theillustrated ordering of such blocks. For instance, some acts or eventscan occur in different orders and/or concurrently with other acts orevents, apart from the ordering illustrated herein, in accordance withthe invention. Moreover, not all illustrated blocks, events, or acts,may be required to implement a methodology in accordance with thepresent invention. In addition, it will be appreciated that theexemplary method 700 and other methods according to the invention can beimplemented in association with the apparatus and systems illustratedand described herein,,as well as in association with other systems andapparatus not illustrated or described.

At 704, film and process parameters associated with an unpatterned waferare obtained, and an optical constant associated with the unpatternedwafer is measured at 706 using an off-line spectroscopic ellipsometer.At 708, metrology instrument parameters associated with a processmeasurement system are obtained. Thereafter, a model is generated orcreated at 710 according to the measured optical constant and themetrology system parameters. Finally at 712, the model is provided to aprocess measurement system via a network before the method ends at 714.

Although the invention has been shown and described with respect tocertain illustrated implementations, it will be appreciated thatequivalent alterations and modifications will occur to others skilled inthe art upon the reading and understanding of this specification and theannexed drawings. In particular regard to the various functionsperformed by the above described components (assemblies, devices,circuits, systems, etc.), the terms (including a reference to a “means”)used to describe such components are intended to correspond, unlessotherwise indicated, to any component which performs the specifiedfunction of the described component (e.g., that is functionallyequivalent), even though not structurally equivalent to the disclosedstructure, which performs the function in the herein illustratedexemplary aspects of the invention. In this regard, it will also berecognized that the invention includes a system as well as acomputer-readable medium having computer-executable instructions forperforming the acts and/or events of the various methods of theinvention.

In addition, while a particular feature of the invention may have beendisclosed with respect to only one of several implementations, suchfeature may be combined with one or more other features of the otherimplementations as may be desired and advantageous for any given orparticular application. As used in this application, the term“component” is intended to refer to a computer-related entity, eitherhardware, a combination of hardware and software, software, or softwarein execution. For example, a component may be, but is not limited to, aprocess running on a processor, a processor, an object, an executable, athread of execution, a program, and a computer. Furthermore, to theextent that the terms “includes”, “including”, with, “has”, “having”,and variants thereof are used in either the detailed description or theclaims, these terms are intended to be inclusive in a manner similar tothe term “comprising.”

1. A method of evaluating parameters of a semiconductor wafer as part ofa manufacturing process comprising the steps of: measuring a pluralityof reference wafers with an off-line scatterometer; determining theparameters of the reference wafers based on the measurements; using amodel and the results of the determining step, to generate a library ofcalculated signatures, each corresponding to a different parameter set;measuring a test wafer with a integrated scatterometer, said integratedscatterometer being integrated with a process tool; and comparing theresults of the measurement of the test wafer to the library ofsignatures to evaluate the parameters of the test wafer.
 2. A method asrecited in claim 1, wherein the parameters include critical dimensions.3. A method as recited in claim 1, wherein the parameters includeoverlay registration.
 4. A method as recited in claim 1, wherein theparameters include the temperature uniformity of a bake process step. 5.A lithograph track processing apparatus comprising: a stand-alonescatterometer, said scatterometer for measuring reference wafers andbased on the measurements generating information corresponding to one ofa measurement recipe and a library of signatures corresponding toparameter sets; and a scatterometer integrated with a lithographic trackprocessing tool, said integrated scatterometer for measuring a testwafer and evaluating process parameters of the test wafer using themeasurement of the test wafer and said information received from thestand-alone tool.
 6. An apparatus as recited in claim 5, wherein theparameters include critical dimensions.
 7. An apparatus as recited inclaim 5, wherein the parameters include overlay registration.
 8. Anapparatus as recited in claim 5, wherein the parameters include thetemperature uniformity of a bake process step.
 9. An apparatus asrecited in claim 5, wherein said stand-alone scatterometer and saidintegrated scatterometer are connected by a network.
 10. A lithographtrack processing apparatus comprising: a stand-alone scatterometer, saidscatterometer for measuring reference wafers and using the measurementsand a model, to generate a library of calculated signatures eachcorresponding to a different parameter set; and a scatterometerintegrated with a lithographic track processing tool, said integratedscatterometer for measuring a test wafer and evaluating processparameters of test wafer based on the measurement of the test wafer andthe library received from the stand-alone scatterometer.
 11. Anapparatus as recited in claim 10, wherein the parameters includecritical dimensions.
 12. An apparatus as recited in claim 10, whereinthe parameters include overlay registration.
 13. An apparatus as recitedin claim 10, wherein the parameters include the temperature uniformityof a bake process step.
 14. An apparatus as recited in claim 10, whereinsaid stand-alone scatterometer and said integrated scatterometer areconnected by a network.